Triplewood Cache Optimizer

July 30, 2025 · View on GitHub

Magento 2 typically sends the following Cache-Control header on HTML responses (excluding static assets):

Cache-Control: max-age=0, must-revalidate, no-cache, no-store

This instructs the browser not to cache any HTML pages. As a result, the browser re-requests the full-page HTML on every navigation, even for back and forward actions, reducing perceived performance.

Caution: This module is recommended only if you run Hyvä on your Magento instance and fully understand the associated security implications. Additionally, this is NOT thoroughly tested yet. It may not cover all security related aspects of your project!

To safely use this module:

  • Do not show any user-specific data on the initial page load for non-logged-in users.
  • Load sensitive data dynamically via AJAX after the page has rendered.
  • Check your varnish-config if you are overriding resp.http.Cache-Control. If so, this extension will not do anything.

Why Magento Does This

  • Magento caches CSS, fonts, JavaScript, and images in the browser, but not HTML pages.
  • This is a safety measure: HTML responses may contain user-specific data (e.g., cart totals, customer name, wishlist count, or prices).
  • If browser caching is enabled and HTML is reused improperly, it may display stale or incorrect data to logged-in users.
  • Magento therefore relies on server-side caching (Varnish or built-in FPC), not browser caching.

The consequences

While cautious, this strategy comes at a cost:

  • Even guest users receive uncached HTML, despite often seeing the same content.
  • This prevents CDNs like Cloudflare from applying their own HTML caching optimizations.
  • Browser features like back/forward caching (bfcache) are disabled, making Magento feel slower than necessary.

What This Module Does

It enables browser caching for non-dynamic guest pages, such as:

  • CMS pages
  • Product detail pages
  • Category pages

The following routes are explicitly excluded from caching:

  • Checkout
  • Customer account pages

Installation details

In your Magento composer.json add the following lines under the "repositories" section:

"repositories": {
    // ..
    "triplewood-de/module-cache-optimizer": {
        "type": "vcs",
        "url": "https://github.com/triplewood-de/magento2-cache-optimizer"
    }
},

You can install this module via composer

composer require triplewood-de/module-cache-optimizer
bin/magento module:enable Triplewood_CacheOptimizer
bin/magento setup:upgrade